Thrombosis, or sometimes refered as thromboembolism, is the clot of blood in a blood vessel or a cavity of the heart. It is usually formed by the interaction of the damaged blood vessel wall with the blood components such as platelet or other clotting factors. The damaged blood vessel wall is usually caused by elevated level of plasma cholesterol or triglyceride or other factors that damaged the lining endothelium. When a blood vessel is damaged, the endothelium is disrupted and an underlying layer of collagen is exposed. The exposed collagen attracts platelets, which adhere to it and liberate clotting factors. The clotting factors in turn rapidly attracts more platelets, and a loose plug of aggregated platelets is formed. The loose aggregation of platelets in the temporary plug is bound together and converted into the definitive clot by fibrin. These clots eventually caused the myocardial infarction and cerebral thrombosis, which are common symptoms among the adults population in the recent years. In spite of intensive researches for an effective anti-platelet aggregation drug, there is no drug to date that can effectively prevent the thrombosis except for the aspirin and dipyridamole, which are known as platelet aggregation inhibitors and used to inhibit the formation of blood clot. Breakthrough has yet to be achieved.
In addition, blood vessel abnormality and blood vessel constriction can also contribute to the formation of thrombosis. The cause to the abnormality of blood vessel is described previously. The blood vessel constriction, also known as blood vessel dilation is seen when blood factors such as prostacyclin (PG12) or endothelium-derived relaxing factor (EDRF) are released, that can relax the blood vessel and increase the blood flow. There is no drug to date that can prevent damages to the endothelium or stimulate the release of the PG12 or EDRF; although several calcium channel blockers such as nifedipine or verapamil can inhibit the calcium influx and cause the blood vessels to relax. The inventor has carefully examined the potential drug for the prevention of thrombosis and found that chelerythrine, the major components of Zanthoxylum simulans, have the activity against the thrombosis. This finding stimulated the inventor to investigate further and complete the present invention.